1. Field of the Invention
The present invention relates to a disk drive apparatus, and in particular to a disk drive apparatus which includes an auto balancing unit capable of automatically balancing (an up and down) movement of a disk when a disk mounted on a turntable of the disk drive is rotated.
2. Description of the Background Art
As a disk drive is designed to operate at a high speed, a rotation unbalance condition (up and down movements) may occur when a disk is driven at a high speed.
The above-mentioned disk unbalance condition result in the problems that a signal recorded on a disk is not accurately reproduced, and a signal is not accurately recorded onto a disk.
The above-described disk unbalance problem may occur due to a nonuniformity of a disk when fabricating the disks. In addition, as the rotation speed of the disk is increased, the rotation unbalance problem of the disk is increased. Also, in the case that the disk is not accurately mounted on the turntable, the above-described unbalance problem may occur.
A conventional auto balancing unit which has been proposed to overcome the rotation unbalance problems of the disk will be explained.
As shown in FIG. 1, on the upper surface of a substrate 1, a rotary shaft is vertically mounted.
A ball casing 9 is installed at a lower portion of a turntable 7 inserted onto an upper end portion of the rotary shaft 6 and is downwardly extended from an outer portion of the turntable 7 and is bent inwardly toward the center of the turntable and is extended to the outer surface of the rotary shaft and is bent upwardly toward the upper portion of the rotary shaft 6 and then is extended to the lower surface of the turntable 7.
The ball casing 9 is formed in a circular plate shape like the turntable 7 and includes a space in which a plurality of metallic balls 10 are provided.
A lower portion of an outer side of the above-described space is rounded in order to implement a smooth movement of the balls 10.
A racing face 9i along which the balls 10 roll is formed at an outer portion of the inner wall of the space formed in the ball casing 9 so that a rotation unbalance which may occur when the disk is rotated is prevented.
A magnet 11 is engaged to an inner central portion of the ball casing 9.
When the apparatus is operated at a low speed or is not operated, the magnet 11 serves to prevent the balls 10 from being freely moved.
A buffering member(not shown) which is made of a rubber is formed on an outer surface of the magnet 11.
A spindle motor 3 is installed at a lower portion of the ball casing 9, and a rotor 5 which is one of the elements of the spindle motor 3 is connected with the rotary shaft 6 for thereby implementing an integral rotation with the rotary shaft 6, and a stator 4 which is another one of the elements of the spindle motor 3 is fixed to an outer portion of a bearing 2 inserted onto a lower outer portion of the rotary shaft 6.
In the drawing, reference numeral 5M designates a magnet forming the rotor 5, and 8 designates a clamp for fixing a disk on the turntable.
The operation of the conventional auto balancing unit will be explained.
First, as the rotor 5 is rotated by the driving operation of the spindle motor 3, the rotary shaft 6 is rotated. The turntable 2 is rotated by the rotation of the rotary shaft 6, and a disk (not shown) mounted on the upper surface of the turntable 2 is rotated.
At this time, when the disk is rotated at a high speed, or if the disk is rotated in a rotation unbalance state, the balls 10 in the interior of the ball casing 9 are moved along the racing face 9i of the ball casing 9 for thereby preventing an unbalanced state of the disk.
However, the above-described disk drive apparatus having an auto balancing unit has the following problems.
Since the spindle motor 3, the ball casing 9 and the turntable 7 are sequentially installed from the lower portion of the rotary shaft 6 installed on the upper surface of the substrate 1, the spaces therebetween are large, so that the entire height of the disk drive apparatus is increased.
Namely, as the spindle motor 3, the ball casing 9 and the turntable 7 are independently formed, the weight of the elements which are driven by the spindle motor 3 is increased, so that a large/high amount of power is required for rotating the spindle motor 3.
Generally, since the ball casing 9 is fabricated using a mold in order to decrease the fabrication cost, the ball casing 9 may be deformed during the operation of the apparatus or when the apparatus is not driven.
Since there is no element for fixing the outer portion of the ball casing 9 contacting with the lower surface of the turntable 7, and the balls 10 which are moved in the interior of the ball casing 9 are made of a metallic material, the outer portion(in particular the portion contacting with the turntable 10) of the ball casing 9 may be deformed by the balls 10 during the operation of the apparatus or may be deformed by an externally applied force during the operation of the apparatus.
If the shape of the ball casing 9 is deformed, a smooth movement of the balls is not implemented. If the racing face 9i which is preferably formed to have a roundness is deformed, it is impossible to implement the auto balancing operation.
Accordingly, it is an object of the present invention to provide an auto-balancing disk drive apparatus which is capable of decreasing a noise and vibration by obtaining a roundness of a racing face formed to guide balls for thereby implementing an effective auto-balancing operation.
It is another object of the present invention to provide an auto-balancing disk drive apparatus which is capable of significantly decreasing the space needed for installing an auto balancing unit for automatically balancing the rotation of a disk.
It is another object of the present invention to provide an auto-balancing disk drive apparatus which includes an auto balancing apparatus capable of decreasing the driving force needed for the rotation of a disk.
In order to achieve the above objects, there is provided a disk drive apparatus which includes a motor generating a rotational force with respect to a rotary shaft, and an auto balancing unit installed radially laterally with respect to the motor for automatically correcting an unbalanced state of a rotation member when an unbalanced state occurs at the rotation member.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.